Novel dibenzo-18-crown-6 ether functionalized bis-benzimidazole derivatives: synthesis and antifungal evaluation

A series of novel 18-crown-6 ether functionalized bis-benzimidazole derivatives (3a-g) have been synthesized by reacting various substituted ortho-phenylene diamines and pyridine diamines with 4,4'-diformyl dibenzo-18-crown-6 ether (1). The required starting material 4,4'-diformyl dibenzo-18-crown-6 ether (1) was prepared by Duff formylation method. All synthesized novel molecules have been identified on the basis of infrared (IR), H-1 nuclear magnetic resonance (NMR), C-13 NMR, mass spectroscopy (MS), and elemental analyses. The title compounds (3a-g) were tested for antifungal activity against Aspergillus niger, Trichothecium sp., Rhizopus sp., and Sclerotium rolfsii fungi species using agar well diffusion method, showing mild to good results.